feat(deploy): drop the IaC layer, and make both apps runnable as containers

Moving the issuer's state into Postgres removed the last thing that tied
either app to one hosting provider. What was left was a deployment tool
describing resources that no longer existed — so this replaces it with
`wrangler`, which is what actually deploys a Worker, and adds a second way
to run each app that involves no provider at all.

Each app now has a `wrangler.jsonc` with an environment per stage, and a
`Dockerfile` beside it. The handler is the same one in both cases; what
differs is only where its settings come from. Two of them gained a second
spelling so that nothing has to branch on the runtime: Postgres arrives as
a pooled binding or as `DATABASE_URL`, and the route to the issuer is a
service binding or `AUTH_INTERNAL_URL`.

That last one is new, and it is a split the binding was already making
without saying so. `AUTH_ISSUER_URL` has to be the issuer's public name,
because it is compared literally against every token's `iss` claim — but
the public name is often not routable from inside a deployment. So the
name and the route are two settings now rather than one that cannot be
both.

DNS moves out of code and into `docs/dns.md`, which lists every hostname
and what it is for. Six records that change roughly never did not need a
tool, and the table outlives whatever is answering the names — which is
the point, since some of them will stop being Workers. The sandbox
hostnames are hyphenated rather than nested for the same reason: a
certificate covering `*.nestri.io` covers one label and not two, so
`api-sandbox.nestri.io` can become an ordinary origin later without a
certificate having to be ordered for it first.

Also drops `EMAIL_DEV_LOG` from committed configuration into `.dev.vars`,
which `wrangler deploy` cannot upload. Printing a live sign-in code to a
log should not be one forgotten override away from production.

apps/auth/README.md

@@ -1,7 +1,8 @@
 # apps/auth
 
-The authentication worker for Nestri — a Cloudflare Worker built on
-[`@nestri/auth`](../../packages/auth/README.md) (OpenAuth-style issuer).
+The authentication service for Nestri, built on
+[`@nestri/auth`](../../packages/auth/README.md) (OpenAuth-style issuer). One
+handler, run either as a Cloudflare Worker or as an ordinary HTTP server.
 
 ## What it does
 
@@ -26,17 +27,28 @@ Hosts the OAuth issuer and the sign-in UI:
 - Authorization codes, refresh tokens and device codes are stored as hashes. Each is a bearer
   credential, so what is kept is enough to recognise one and not enough to present it.
 - JWT subjects are defined in `@nestri/core/auth/subjects`.
-- The API worker verifies tokens against this issuer through `AUTH_ISSUER_URL`.
+- The API verifies tokens against this issuer through `AUTH_ISSUER_URL`, which must be this
+  service's **public** URL: a token carries the address it was minted through and the check is
+  literal.
 
 ## Structure
 
 ```text
-src/index.ts      # Worker entrypoint: issuer config, stores, success callback
+src/index.ts      # The handler: issuer config, stores, success callback
+src/server.ts     # The same handler behind a listening socket
 src/email.ts      # Verification code delivery
-test/             # Worker tests
+wrangler.jsonc    # Worker configuration, one environment per stage
+Dockerfile        # The container, built from the repository root
+test/
 ```
 
 ## Running
 
-Deployed through Alchemy (`apps/auth` worker in `alchemy.run.ts` at the repo root). Its only
-stateful binding is `HYPERDRIVE` (Postgres), alongside the mail settings.
+```sh
+bun run dev      # under the Workers runtime, on :1337
+bun run serve    # as a plain process, on $PORT (default 1337)
+```
+
+Its only stateful dependency is Postgres — as a `HYPERDRIVE` binding on Workers, or as
+`DATABASE_URL` anywhere else — alongside the mail settings. Full list and deployment steps:
+[`docs/deploy.md`](../../docs/deploy.md).